You can disguise your spells as part of your performance.
Prerequisites
Bardic music, Perform 9 ranks.
Benefit
You have mastered the art of casting spells unobtrusively, mingling verbal and somatic components into its music and performances so that others rarely catch you in the act of casting a spell. Like a silent, stilled spell, a disguised spell can’t be identified through Spellcraft. Your performance is obvious to everyone in the vicinity, but the fact that you are casting a spell isn’t. Unless the spell visibly emanates from you or observers have some other means of determining its source, they don’t know where the effect came from.
Level Increase: +1 (A disguised spell uses up a spell slot one level higher than the spell’s actual level.)